Software for Drawings?

I work with diesel generators and AC electrical projects in general. Besides the obvious AUTOCAD, is there a software that I can use for doing my own iterations of drawings for projects for my customers?

These are very simple and I am sort of getting my things done with Excel or PowerPoint but it's very primitive.

Just Google "free CAD software" and you'll get tons of choices. If you actually use AutoCAD, look for one that works with compatible file formats.

I have always used traditional drawing programs, like Adobe Illustrator. (I prefer a different one, but Adobe bought and killed it.) These days I use Intaglio, which is a very able competitor. Drawing programs are not purpose-built for CAD, though, and you might have to draw your own libraries. This would not be a problem if you're getting by with Excel or Powerpoint.

I have used AutoCad since the DOS days and over time have acquired an extensive library of blocks for schematics Electrical/PLC-Ladder/Electronic/Hydraulic-pneumatic etc.
There has always been a bit of a steep learning curve to Acad however.
You might be able to modify and create libraries using free Kicad, but it is basically designed for Printed circuit design.
But once you have the block libraries it should work.
Max.